Quality control on finished cement includes strength testing at
Answer: C
Testing at several ages shows both the early gain and the ultimate figure, which together characterise the cement. The 28-day result is the one most standards use for the strength class. Earlier ages are reported as an indication of setting behaviour.
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Consider the following statements about cement mill control.
1. Fineness is used as the primary control variable.
2. Mill temperature is limited to protect the gypsum.
3. Strength testing provides real-time control of the mill.
Answer: D
The first two are correct. The third is wrong on timing, since a strength result takes days to obtain and can only confirm what was made rather than control what is being made now. Every quality system distinguishes control from verification.
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State whether the following is true or false.
A single cement mill can produce several different cement types.
Answer: A
Correct answer: True
One mill serves several products by changing the feed proportions and the target fineness - ordinary Portland, a blended cement with slag or fly ash, a limestone cement, a finer rapid-hardening grade. The constraints are the cleanout between campaigns and enough silo capacity to keep the products apart.
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The specific surface required of a cement is decided principally by
Answer: B
A higher class generally needs a finer grind, and the setting characteristics follow from the same figure. Colour, storage and transport have no bearing on the fineness target. Fineness follows from the performance the cement must deliver.
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